Is there a reason that some of Brian May's like Roadgames, Snapshot, Harlequin, Thirst, Race for the Yankee Zephyr, and Patrick( My favourite and I still have the Varese Record) haven't been newly released on CD.

Is there a reason that some of Brian May's like Roadgames, Snapshot, Harlequin, Thirst, Race for the Yankee Zephyr, and Patrick( My favourite and I still have the Varese Record) haven't been newly released on CD.